In the operation of internal combustion engines, it is necessary to provide adequate lubrication of the engine parts to minimize wear, which normally does not present a problem when the engine is being operated, but presents numerous problems when the operative cycle of the engine is being initiated.
Wear of engine parts is only partially dependent upon engine operation and, generally, is maintained at a minimum when the engine is operated for a continuous, albeit substantial, period of time. Lubricating systems of most internal combustion engines are generally more than adequate for maintaining a steady and ample supply of lubricant to the engine parts while the engine is operating. It is well known that a vehicle driven steadily for a relatively long period of time over a long distance, for example, will experience substantially less engine wear than one that it subjected to numerous stops, e.g., one that is driven on a plurality of frequent, short trips, even though the total mileage of the latter vehicle may be substantially less than that of the vehicle that is driven steadily. It has been determined that approximately seventy to eighty percent of the engine wear occurs during the first ten to fifteen seconds of operation of the vehicle, and hence the engine, and it is to the alleviation of such wear that the present invention, as well as numerous prior art arrangements, is directed.
In U.S. Pat. No. 4,502,431 of Lulich there is shown a pre-combustion diesel engine lubrication system wherein the starter motor is sued to drive an oil pump prior to cranking the engine being cranked. Actuation of the starter motor occurs when the starter switch is moved to the heat position, which is common in diesel engines, but not gasoline engines, for example. The operator must wait before initiating cranking, not only for the pre-lubrication, but for the glow plugs to heat the cylinders and the oil.
Application of lubricant under pressure to the engine parts is shown in U.S. Pat. Nos. 3,556,070 of Holcomb, 3,583,525 of Holcomb, and 3,583,527 of Raichel. In the inventions of these patents, oil is stored under pressure in an accumulator, and is released upon actuation of the starter switch. Thus, generally, the oil is released as engine cranking commences. Such arrangements require a reservoir of oil under pressure even when the vehicle is idle, which is both difficult to achieve and complicated, and is vulnerable to leaks, as well as presenting a safety hazard. Also, although the oil is delivered under pressure, delivery does not occur until the cranking of the unlubricated engine commences, thus wear is still present, although reduced somewhat.
U.S. Pat. No. 4,199,950 of Hakanson et al disclosed a lubrication system wherein oil is delivered in a high pressure spray as starting commences. This arrangement is similar to those discussed in the foregoing in that cranking and lubrication commence simultaneously, hence there is some unlubricated movement of the engine parts.
A prior art arrangement which does not rely on cranking to start the pre-lubrication is shown in U.S. Pat. No. 4,628,877 of Sundles et at. The system of this patent requires that the ignition and switch be turned to the "ON" position, which energizes an auxiliary oil pump which pre-lubricates the engine, after which the switch is turned to the"START" position and the engine is cranked. For the system to work properly, the operator, as is also the case in the Lulich patent, must wait an interval of time before cranking the engine.
From the foregoing it can be seen the that prior art systems, for the most part, allow some unlubricated engine action prior to pre-lubricating. Those systems that pre-lubricate before any engine movement require the operator to wait a period of time before cranking the engine.